Draw-plate for preparing fibrous filaments for electrical carbons



(No Model.)

J. H. GUEST.

DRAW PLATE FOR PREPARING FIBROUS FILAMENTS-FOR ELECTRICAL OARBONS.

No. 256,212. Patented Apr. 11,1882.

WIN

N. PETERS. vhvwulho n her. Washington. 04 c.

UNITED STATES PATENT OFFICE.

JOHN H. eunsr, or BROOKLYN, NEW YORK.

- DRAW-PLATE FOR PREPARING FlBROUS FILAMENTS FOR ELECTRICAL CARBONS.

SPECIFICATION forming part of Letters Patent No. 256,212, dated April 11, 1882.

Application filed Septc1nber24,188l. (Nomodel) To all whom it may concern:

Be it known that I, JOHN H. GUEST, of Brooklyn, Kings county, New York, have invented an Improved Draw-Plate for Preparing Fibrous Filaments for Electrical Oarbons, of which the following is a specification.

This invention consists more particularly in a simple tool or draw-plate especially adapted for drawingor reducing fibrous orfragile strips of wood or other material for the production of carbon loops forincandescent electriclamps, but which may be also used for drawing other materials.

It is now well known that carbons for incandescent electric lamps are commonly produced from fine strips. of some tough'close-grained wood or fibrous substance, and that bamboo is 110w preferably used for this purpose. This bamboo is first cut or slit upinto slender sticks or strips, and these are then reduced dowirto the desired size and uniform thickness in cross section by drawing them through the successive holes ofa wire draw-plate till the strip is reduced to the form of a mere thread, and of regular shape and thickness throughout. Now, the ordinary wire draw-plate, as is well known, has a number of holes of gradually-decreasing size, but each hole has a definite and fixed caliber; and to draw the bamboo strip it is first necessary to pare off its tip, then insert the strip in the first hole, seize its protruding end with,a nippers, and then draw the strip through the plate, after which the same operation is repeated successively at the other holes of smaller sizes till the strip is reduced to the desired fineness. Theseoperations, while easy in the case of wire, owing to the metallic nature and strength of wire, are difficul't in the case of comparatively weak and fragile wood, and have to be conducted with great delicacy and care, and even then a large proportion of the filaments are broken and injured in the process and rendered worthless, for the parin g of the ends of the strips, which are already'very fine, greatly weakens and reduces them, and.

renders it frequently impracticable to obtain any firm grasp thereon necessary to draw them through the plate.

Now,'tl1e objectof my improvement is to provide a draw-plate in which the holes will be of practically adjustable caliber, and which may be at first dilated, so to speak, to admit the end of the strip,and then contracted slightly thereon, so that the strip may be freely inserted without'a-ny paring of its ends, and then firmly seized by its strong end and drawn through, and by successive drawings, after slight successive contractions of the hole, the strip may be thus reduced to the desired ga'gein an easy gradual manner without putting much strain on the strip or weakening or reducing itsgrasping ends, whereby the operation of drawing the fibrous filaments may be conducted rapidly and easily and with little or no breakage.

The main portion of my invention therefore consists in the features here outlined, as hereinafter fully set forth.

Figure 1 of the annexed drawings gives a side elevation of my improved draw-plate, and Fig. 2 a plan view thereof, partly in section on the line 00 so of Fig. 1, with a fibrous strip represented in the act of being drawn through the plate. Fig. 3 represents a modification.

My improved tool consists of two plates, a b, fitted closely against each other, and preferably of circular form, pivoted to each other at the center by a strong stud, c. From each plate extends a long lever-arm, a b, which at their ends are bent or formed so as to overlie each other, and are joined by an adjustingscrew, (1, which works through a smooth hole in the upper arm and screws into a threaded hole in the lower arm, as. illustrated in Fig. 1.

The screw is provided with a broad-milled head or knob, e, whose hub bears upon the upper arm, so that by turning the screw in its direction of advance the arms will be caused to approach and the plates at I) moved slightly upon each other, and by turning the screw in the opposite direction, the arms will be diverged by the action of a strong spring, g, which encircles the screw between the arms and bears at opposite ends on the arms, as seen inFig.-1.

The plates a b are perforated with a similar set of holes, which are preferably arranged in circles and of varying sizes, the smaller series I I A Now, it will be understood that when the adjusting-screw d is set in its normal or zero position the holes in both plates will perfectly coincide, as in Fig. 1; but if this screw is turned slightly the plates will be moved slightly upon each other and one hole moved out of coincidence with the other, as in Fig. 2, thus contracting the apertures through the two plates or practically "contracting the caliber of the draw-holes, as will be understood.

In order to indicate the exact degree to which the holes may be adjusted and to enable the same a justment or caliber to be at any time obtained, as required, the head of the screw is graduated, as shown in Fig. 2, and a fixed index-point, f, projects from the arm over these graduations. Hence when the zero of the graduations matches with the index-point the holes of the plates will exactly coincide and will be set to their full effective caliber; but if the screw is turned or advanced away from this point, the plates will be moved correspondingly, and theholes moved slightly"ontpllgoincidence, so that their effective caliber wilTbe reduced in proportion to the degree to which the screw is turned, which will be indicated by the graduations, and hence veiy slight decreases of the caliber may be thus made, and any exact decrease or increase may be at any time obtained, and the work reduced very gradually and easily, and always drawn to a uniform gage.

Now, in using my improved tool the strips from which the carbons are to be made are first roughly formed in the usual way by splitting np the bamboo or other substance into slender sticks or strings, and the end of one of these strips is then inserted in one of the drawholes of the tool which is the nearest easy fit therefor, while the tool is set at its zero-point, as before described, with the holes at their full caliber. The screwis then adjusted so as to move the holes slightly out of coincidence, as before described, which will of course cause the hole or holes in which the strip is inserted to'contract, so to speak, upon the strip, as shown in Fig. 2that is, one side of the hole in one plate will press against one side of the strip and force the opposite side of the strip against the opposite side of the hole in the other plate. The inserted and protruding end of the strip is now seized by a nippers and the strip drawn through the plate, when a light shaving, orv rather an infinitesimal portion,will be removed from one side of the strip, and its size thus slightly reduced and the strip rendered more smooth and uniform.

It will beobserved on reference to Fig. 2 that where the holes of the two plates junction at the meeting faces of the plates the opposite angular edges of the respective holes are forced against and press or pinch the strip between them. Hence when the strip is drawn through between these approaching edges the edge which presents an acute angle to the ad- Vance of the strip will act as a cutting, or

rather scraping, edge, to scrape off or remove a slight portion of the strip, as illustrated in Fig. 2, while the opposite bearing-edge of the other hole, being at an obtuse position, will act chiefly to support the opposite side of the strip and to smooth and compact the same; hence the substance is removed mostly, if not altogether, from one side of the strip, while the opposite side is smooth and compacted, thus rendering the strain on the strip much less, and tending to increase the density and toughness of the strip, and at the same time giving it a tendency to curl in one direction, which assists the subsequent bending of the strip into the form of a loop. After the strip is thus drawn through the hole once, its end is again inserted in the same hole, and the screw is again adjusted to contract the caliber a little further, and the strip is again drawn through, thus reducing it a little more; and these operations may be repeated successively till the strip is drawn down to the required fineness. This may all be done by the successive slight contractions of one pair of holes; but if a finer strip is required the strip may be finished by being finally drawn through the next finer pair of holes, aswill be understood; and by the means described of contracting the holes at each successive drawing by infinitesimal degrees the reduction of the strip is accomplished gradually with great perfection and without putting much strain on the strip, and by means of the scale and index all the strips can be drawn to a uniform gage. Hence the work may be performed much. more quickly and accurately than by the crude system heretot'ore adopted, and with very few breakages of the strips, and the finished strips will possess greater uniformity and strength, as the fiber in them will be much less strained or displaced, and they will hence produce much better carbon loops, thus accomplishing a material improvement in the manufacture thereof.

The finished strips drawn by this tool will of course be slightly oval in cross-section; but this is not objectionable. If, however, the holes of the plate be made oval, then the strips will be drawn circular, or nearly so, as will be understood..

Instead of making the tool with coinciding holes in both plates, as shown in Figs. 1 and 2, the tool may be made as illstrated in Fig. 3- that is, having a set or row of holes in one of the plates only, while the edge of the other plate is arranged to move over the holes presenting a beveled edge thereto, as seen at i in the cross-section. This construction is, however, much inferior to the first, and is not rec ommended, although its principle is similar,

-but not so complete.

In Figs 1 and 2 I have shown the plate a, which may be called the fixed plate, as being formed with a base, a, by which it may be fixed to a bench or other support; but this is not essential.

I am of course aware that wire-cutting devices have been made with two perforated plates, movable over each other by means of levers or other mechanical powers, so as to sever or shear ofi the wire inserted in the holes of the plates; but such devices are obviously distinct from a draw-plate constructed with two coincidentally-perforated plates, adjustable over each other for the purpose described, and provided with means for so relatively adjusting the plates and for retaining them rigidly at the desired adjustment.

What I claim is 1. A drawing plate or tool formed with .two' plates fitted closely against each other, and adjustable upon each other in such manner that the aperture or effective caliber of the draw-holes is reduced by the movement of one plate over the other, and provided with ameans for so adjusting the plates and retaining them firmly at the desired adjustment, substantially as herein shown and described.

2. A draw plate or tool formed with two overlying plates, perforated with a coinciding set of draw-holes, and with means of moving or adjusting the plates overor upon each other, and of holdingthem firmly at such adjustment, so as to bring the holes out of coincidence more or less, and so retain them, substantially asand for the purpose set forth.

3. A draw-toolformed with two overlying plates fitted closely against each other, and each perforated with a coinciding series of draw-holes having a flaring or tapering form, arranged with their narrow ends meeting at the meeting faces of the plates, and with means for moving or adjusting the two plates upon each other, so as to bring the tapering holes out of coincidence more or less, substantially as herein shown and described.

4. A draw-tool constructed with two plates fitted against and pivoted'or jointed to each other, with an adjusting-screw connecting the two plates, whereby the turning of said screw moves the plates upon each other and causes the draw-holes to be partly obstructed or contracted by the movement of one plate over the holes of the other, and at the same time enables the plates to be held at such adjustment, substantially as and for the purpose herein set forth. a

5. The combination,with a draw-tool formed with two overslidin g plates, in which the drawholes are contracted or obstructed by the movement of one plate onthe other, of an adjusting-screw connecting with and serving to converge or diverge the plates, and a series of graduations on said screw with an index-point afiixed to one of the plates, substantially as and for the purpose set forth.

JOHN H. GUEST.

Witnesses:

CHAS. M. HIGGINS, J NO. E. GAVIN. 

